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The CPT® Code 85293 refers to a laboratory test known as the high molecular weight kininogen assay, also referred to as the Fitzgerald factor assay. This test is specifically designed to measure the activity of high molecular weight kininogen (HMWK), which is a crucial plasma protein produced by the liver. In its inactive form, HMWK circulates in the bloodstream until it encounters an injury to the epithelium, at which point it binds with prekallikrein and factor XI. This interaction is essential for the activation of factor XIIa, which plays a significant role in the intrinsic pathway of the clotting cascade. A deficiency in HMWK is a rare condition that typically does not lead to spontaneous or excessive bleeding. Instead, it is often identified when a patient presents with an abnormal bleeding time test, specifically the activated partial thromboplastin time (PTT). The underlying causes of HMWK deficiency are usually linked to rare inherited genetic disorders; however, it can also be acquired in patients suffering from liver disease or disseminated intravascular coagulation (DIC). To perform this assay, a blood sample is collected through a venipuncture, which is reported separately. The plasma obtained from this sample is then subjected to a clotting activity assay to evaluate the functionality of HMWK in the coagulation process.
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The high molecular weight kininogen assay (CPT® Code 85293) is indicated for the evaluation of patients who may have a deficiency in high molecular weight kininogen, particularly when abnormal bleeding times are observed. The following conditions may warrant the performance of this assay:
The procedure for conducting the high molecular weight kininogen assay involves several key steps to ensure accurate measurement of HMWK activity. First, a blood sample is obtained from the patient through a venipuncture, which is a standard method for collecting blood. This sample is crucial as it provides the plasma needed for the assay. Once the blood is collected, it is processed to separate the plasma from the cellular components. Next, the plasma is subjected to a clotting activity assay specifically designed to evaluate the functionality of high molecular weight kininogen. This assay measures how well HMWK interacts with other components of the coagulation cascade, particularly its role in activating factor XIIa. The results of this assay will indicate whether the HMWK levels are within normal ranges or if a deficiency is present, which could explain any abnormal bleeding tendencies observed in the patient.
After the high molecular weight kininogen assay is completed, the results will be analyzed to determine the activity level of HMWK in the patient's plasma. If a deficiency is identified, further evaluation may be necessary to understand the underlying cause, whether it be genetic or acquired. Patients may not require specific post-procedure care related to the assay itself, but any findings should be discussed with the healthcare provider to determine the appropriate next steps in management or treatment. Additionally, it is important to monitor the patient for any signs of bleeding or other complications that may arise from underlying conditions related to HMWK deficiency.
| Short Descr | CLOT FACTOR WGHT KININOGEN | Medium Descr | CLOTTING HI MOLEC WEIGHT KININOGEN ASSAY | Long Descr | Clotting; high molecular weight kininogen assay (Fitzgerald factor assay) | Status Code | Statutory Exclusion (from MPFS, may be paid under other methodologies) | Global Days | XXX - Global Concept Does Not Apply | PC/TC Indicator (26, TC) | 9 - Not Applicable | Multiple Procedures (51) | 9 - Concept does not apply. | Bilateral Surgery (50) | 9 - Concept does not apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 9 - Concept does not apply. | Co-Surgeons (62) | 9 - Concept does not apply. | Team Surgery (66) | 9 - Concept does not apply. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | CLIA Waived (QW) | No | APC Status Indicator | Conditionally packaged laboratory tests | Type of Service (TOS) | 5 - Diagnostic Laboratory | Berenson-Eggers TOS (BETOS) | T1H - Lab tests - other (non-Medicare fee schedule) | MUE | 1 | CCS Clinical Classification | 233 - Laboratory - Chemistry and Hematology |
| 90 | Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number. | Q4 | Service for ordering/referring physician qualifies as a service exemption |
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| 2013-01-01 | Changed | Short Descriptor changed. |
| Pre-1990 | Added | Code added. |
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